This invention relates to a solar heat collector, and more particularly to improvements on the vapor condensing portion of a solar heat collector having a heat pipe and a solar heat collection plate in an evacuated transparent housing.
A solar heat collector using a heat pipe, generally, is constructed as follow: A solar heat collection plate exposed to solar rays is disposed in an evacuated transparent pipe, and contacts with the heat pipe which contains an evaporable working liquid and is connected to a heat releasing pipe. The heat releasing pipe communicates with the heat pipe and encloses a heat medium pipe so as to form an annular chamber.
In this solar heat collector, the heat collection plate heated by solar rays heats the evaporable working liquid in the heat pipe to evaporate it thereby producing vapor. The vapor rises upward in the heat pipe, reaches the annular chamber, and is cooled there by the heat medium pipe to condense. The condensate descends and its heated again.
In order to effectively use the heat collected by the heat collection plate, it is necessary to absorb sufficiently the heat of the vapor. Therefore, various means for absorbing the vapor heat are proposed, one of which is desclosed in Japanese Laid-open Utility Model Application No. 55-162061 in which a part of a heat medium pipe is corrugated to provide a large surface contacting with the vapor and heat medium. The heat medium pipe with such a corrugated surface is improved on heat transfer between the vapor and the heat medium, as compared with a flat pipe.
It is desired, however, to further improve the heat transfer without making the scale larger. The heat medium pipe disclosed in the abovementioned Application seems to reduce the cross-sectional area of the passage for allowing the heat medium to flow by the corrugations. Therefore, it seems to prevent the whole construction from reducing the scale.